以devise_invitable的邀请形式添加自定义字段的验证

Question

据我所知,设计只对电子邮件和密码进行验证,可以在初始化程序devise.rb中重新配置:

  # ==> Configuration for :validatable
  # Range for password length. Default is 6..128.
  # config.password_length = 6..128

  # Regex to use to validate the email address
  # config.email_regexp = /\A([\w\.%\+\-]+)@([\w\-]+\.)+([\w]{2,})\z/i

如何添加自定义字段的验证,已添加到devise_invitable的邀请表单中？

例如,我需要验证表单中的first_和last_名称:

= simple_form_for resource, :as => resource_name, :url => invitation_path(resource_name) do |f|
  = f.input :first_name
  = f.input :last_name
  = f.input :email
  = f.button :submit

提前致谢!